Well-being Material Library

Assoc. Prof. Dr. Apichat Praditsmanont attended the launch of the Travel Tech Startup 2024 contest

How Biomass Ash Can Make Construction Greener

Did you know that each megawatt of electricity from biomass also generates 200-400 tons of ash?What is biomass ash and why does it matter?Biomass ash is waste from generating electricity with biomass. Different types of biomass produce varying amounts of ash, typically in the range 1-3%. The more electricity, the more ash.Thailand has 226 biomass power plants totaling 2,110 MW. These plants produce nearly 1 million tons of biomass ash each year. So how do we manage such an enormous amount of ash?Proper management of biomass ashBiomass ash is industrial waste and must be disposed of according to environmental regulations. Common disposal methods include sending it to landfill, using it in cement kilns, composting it for fertilizers and soil conditioners, and recycling it for other usesBut the large volume of biomass ash means high disposal costs. Managing 80,000–100,000 tons can cost 10-15 million baht. To reduce disposal costs and boost the value of biomass ash, research has explored uses in construction materials.Can biomass ash be used in cement?Cement is a key material in concrete production. In a hydration reaction it forms calcium silicate hydrate (C-S-H) that strengthens concrete. Replacing cement with biomass ash significantly affects the properties of concrete.Biomass ash mainly consists of calcium oxide (CaO) but has lower amounts of silica (SiO₂), alumina (Al₂O₃), and iron oxide (Fe₂O₃), resulting in reduced hydration reactions. But SiO₂, Al₂O₃, and Fe₂O₃ can still undergo a pozzolanic reaction with calcium hydroxide (Ca(OH)₂), forming C-S-H. This reaction enhances the long-term compressive strength, sulfate resistance, and acid resistance of concrete while reducing efflorescence on concrete surfaces.Excessive biomass ash content, however, reduces concrete compressive strength. Biomass ash has smaller particles and is lighter than cement, making the resulting concrete lighter. Its high porosity and surface area also lead to greater water absorption, requiring an increase in water content during the mixing process.Appropriate uses and proportions of biomass ash in constructionThe properties of biomass ash significantly impact concrete performance, depending on its type, chemical composition, and quantity. Using biomass ash is most suitable for non-load-bearing applications, such as curbstones, pavement materials, garden decorations, and ventilation blocksThe recommended replacement ratio for cement is 10-30% by weight, but this depends on the type and quality of biomass ash, concrete composition, and mix proportions.Adding value to biomass ash productsTo compete in the market, biomass ash-based products should have unique features, whether in design, aesthetics, or special functions. This approach not only enhances product competitiveness but also contributes to a sustainable circular economy.Story by: Supunnapang Raksawong, Materials Researcher in Sustainable Building Material, RISCReferencesDepartment of Alternative Energy Development and Efficiency, Ministry of Energy (2025). Biomass Power Plant Location Map in Thailand.Kwancheewa Yongstar, Nuanan Kurakaew, Chukiat Chusakul, and Sunan Monkaew (2024). Development of Interlocking Bricks from Waste Rock Dust and Rubberwood Ash. RMUTP Journal of Science and Technology, Vol. 18, No. 1 (2024).Saroj Damrongsil (2007). Effects of Sugarcane Bagasse and Fly Ash Blended Cement on the Physical and Mechanical Properties of Concrete. KMUTT Journal of Research and Technology, Vol. 30, No. 3, July-September (2007).Ayobami A. B. (2021). Performance of Wood Bottom Ash in Cement-Based Applications and Comparison with Other Selected Ashes: Overview. Resources, Conservation and Recycling, Vol. 166, 105351.